public class Pillar{
  Geometry bottom;
  double height;
  Pillar(Geometry bottom,double height){
   this.bottom=bottom;this.height=height;
  }
  public double getVolume(){
  if(bottom == null){
   System.out.println("没有底，无法计算面积");
  return -1;
   }
   return bottom.getArea()*height;
  }
}
